A variety of products, such as comestibles, require packaging material being resistant to moisture-vapor and gas transmission so that the products themselves do not deteriorate due to migration of moisture or gas into the product from the environment or due to loss of moisture or certain gases from the product itself to the atmosphere. Such packaging material must not only have such excellent barrier properties, it must also be resistant to fracturing so that it can be placed about various shaped packages and sealed without loosing its moisture and vapor barrier properties due to cracking in areas where it has been bent, folded, sealed and the like.
A variety of laminates has been proposed for this purpose involving combinations of plastic and metal films, none of which are entirely suitable either in terms of their moisture-vapor and gas transmission rates and fracture properties or in terms of cost. In some instances, the laminate material proposed for wrapping is itself of such a thickness and weight as to be unsuitable for use either in terms of the added cost or in terms of being able to be properly handled by conventional overwrapping apparatus conventionally used in packaging products.
In short, it has not been heretofore possible to have a suitable packaging film which was useful as an overwrap for containers to ensure long term shelf life for the product packaged. The products, as noted, are those that are susceptible to a deterioration due to migration of moisture-vapor and/or gases from the product or to the product through the packaging material.